The only MMO I have played is wow.

I really like the way wow plays and relates The PVP on wow is decent if you're on a PVP server. As with anything it sucks when someone 50 levels above you kills you--but that's life.

I wouldn't mind having the ability to "morph" your character into something else while the game is playing. Nothing sucks like rolling a character and then 40 levels latter realizing that hey--maybe I wanted to be something else. I think this could work if you had different class trainers. I have heard that guild wars is similar in this that you can be a warrior with "X" as your secondary character type build. Where X can be changed.

I always thought that was a great idea and gives you more to work with then the three talent spec trees that WOW gives you.

I could probably think of more if I really sat down and thought about it